Stand up to Mobility scooter conversion

[puddleglum]

I had an idea some time ago to convert a stand up scooter to a lightweight mobility scooter that would fold and be compact enough to travel with and not take up the whole trunk. The design goal was to meet the size and weight requirements to travel as standard luggage on a plane (62" total of LxWxH and 50lb). I found out later that a mobility device is exempt from those requirements, which is good because it ended up a little heavy. It is close though and takes a lot less room than a wheelchair. I started with this:and bought this one as well for parts:. After much thought and debating over how to add something on to the existing scooter to make it work, I gave up, cut the whole thing apart and started over. I've ended up with this: So far it works pretty good, although it needs a few tweeks to get it right.

[amberwolf]

Looks pretty nice. Got any more pics of the in-between process?

[puddleglum]

Thanks, yes I do have some build pics. I'll post some more when I get a chance.

[puddleglum]

My initial thought for this project was to make stabilizer wheels that would fold out of the way but I couldn't find a way to make it fold up as small as I wanted and still make it stable. My other limitation was I have a very limited supply of tools and materials at my disposal, so I had to be able to make it work with what I had. My simple project got complicated really quick. I finally settled on this design, not because I thought it was best, but because I could build it. So, here are some pics of the process. I decided it needed to be fwd if it was only driving one of three wheels. I stripped the scooter down, and laid out where I had to chop the frame to make the back,the front fork.
Then welded in a new crossmember at the rear, cut the frame and fork apart, installed the stem in the new crossmember and figured out where the motor mount had to go.
I had to build a reduction gear on a jackshaft to reduce the speed and built a new brake mount as well because the original did not center the caliper on the disc.

[puddleglum]

I replace the original rear crossmember with a wider one and installed the seat tube. Note: welding the gussets to the front of the post instead of the sides was a bad idea. It caused the seatpost to warp and created a LOT of extra work. The rear of the frame also had to be extended and a mounting bracket designed for the rear axle. Here is the completed frame.

After moving the drive to the front, the downtube arms were interfering with the new front fork, plus one was bent a little when I bought it(didn't see it when I was negotiating price unfortunately) so I had to design and build a new downtube ass'y. and a new support for it. I also added foot pegs for a wider foot placement. Here are all the big pieces completed,


and the front end subassembly powdercoated and ready to go.

I used the wheels from the smaller scooter for the rear and utilized the brake for a parking brake. The lever is a friction shift lever mounted to the riser arm. The axle splits in two for transport and locks to the frame with a dowel pin and a threaded knob for each half.

The seat back is in three pieces so it can fold easily and is spring loaded with an internal elastic cord.
the seatpost has to telescope in three sections to make it collapse far enough and the seat is from Canadian tire. Size was in its favor although a larger seat would have been more comfortable.

[puddleglum]

The new battery box is aluminum channel with a tin floor. The fuse holder is mounted for easy access.



The original was a little shallow for the new Ping 24v 15ah pack but the new one fits perfectly.



I made a new control box up front to house the controller, switches and wattmeter. I am not totally satisfied how this part turned out, so it may get a rework at some point. The switch in the side is a battery disconnect.




Unfolded dimensions are 42l x 26w x 35.5h, so it is comparable to production scooters and larger than the compact travel scooters. Weight is about 56.5lb. Folded dimensions are 33l x12w x18h. It's only 10.5"wide but the tires stick past the sides. The suitcase is there for reference.




Things still to do:
Make a front fender and chain guard.
Remove or disable the freewheel.
I left it on to reduce power consumption, which it does, but having some motor drag on the downhills would help out the brake. I'm open to suggestions on an easy way to do this.
Find a way to limit the top speed, preferably without having to change the gearing.
It does 13-14kph which is still too fast for a mobility scooter and has lots of torque. Does anyone know an easy way to limit the speed of a hall effect throttle?
Change the heavy gauge wiring connectors Andersons. I didn't get them in time for the initial assembly.
I may also try the 250w motor/controller just to see which one woks best for the application.

[amberwolf]

Thanks for these pics; they are very helpful in seeing how you did what you did.

[The fingers]

Wow all over, nice backrest for the seat!